`resolveCollapsedFlagOnRows` puts panel in wrong row

[nmyk]

Hi! I ran into issue #145 and attempted to resolve it by calling util.panel.resolveCollapsedFlagOnRows on the final panel array. This resulted in one of my panels getting moved to the wrong row.

In the following example, I expect stats a and b to be next to each other on row 1; and c, d, and e, on row 2. However, Grafana puts stat b in row 2:

local g = import 'github.com/grafana/grafonnet/gen/grafonnet-latest/main.libsonnet';
local row = g.panel.row;
local stat = g.panel.stat;

local panels = [
    row.new('row 1')
    + row.withPanels([
        stat.new('a')
        + stat.panelOptions.withGridPos(h=8, w=12),
        stat.new('b')
        + stat.panelOptions.withGridPos(h=8, w=12, x=12)
    ]),
    row.new('row 2')
    + row.withPanels([
        stat.new('c')
        + stat.panelOptions.withGridPos(h=4, w=4),
        stat.new('d')
        + stat.panelOptions.withGridPos(h=4, w=4, y=4),
        stat.new('e')
        + stat.panelOptions.withGridPos(h=8, w=20, x=4)
    ])
];

g.dashboard.new("bug report")
+ g.dashboard.withPanels(
    g.util.panel.resolveCollapsedFlagOnRows(panels)
)

[Duologic]

I suggest ensuring all panels and rows have x and y configured. The behavior around rows and gridPos is not very well defined in Grafana so without all the gridPos values set it may become unpredictable.